Bike not running right after Xmas lay-up...

[mick43]

Quick summary...

Got her started, ticking over a bit rough.. went out on road, bike not pulling unless I use choke.. return home..

So I think I've got a fuel/mixture problem... did some searching here, and checked air screw in approx right place (1.5 turns out and ok).

Took carb off (AMAL mono bloc) and cleaned as much as I could understand... i.e. cleaned inside float chamber, checked valve in float chamber ok... cleaned tickler as for some reason this was a bit 'sticky', took out idle and air screws, cleaned (sprayed carb cleaner down) and the same for the main jet assembly. There was a another chrome screw on the side that is a damaged - so I left that alone.

Put carb back on, tickled and she fired up first time (made me jump as never down that before..)..seemed to be running fine, nice and smooth in garage..... couldn't try a road test until today... didn't start so easily, but did start... went out on road... didn't pull at all well, choke made a little difference, then conked out...

So what to do... I'm assuming mixture settings ok etc, as nothing has changed over winter... is this is fuel quality issue ? ie. should I drain down and use new fuel before having to go to a mechanic ?

many thanks in advance...

PS i didn't separate throttle and choke cables from top of carb assembly (couldn't see how to do this) but again I did spray and cleaned with carb cleaner...

(please forgive my lack of knowledge...)

[Ethelred]

First off I'd get a manual and parts listing. Loads of free stuff available on this site and others. Go to the Amal website and there's lots of helpful diagrams and explanations. Sounds like you've been doing some research already, keep reading and search this site as well, most starting problems have been discussed before.
You might just have gummed up jets, the sticky tickler would seem to indicate that's a possibility, so have a look at the Amal site then take out the jets, main, needle and pilot, and use the carb cleaner on them, and the needle itself (be gentle).
Could it have got any damp or condensation it it where it's stored, in which case remove the magneto cap and run a hair dryer over it.
You might have a sticky engine valve, a shot of redex or similar often cures that.
Might even be clogged up petrol taps, have you tried it on the other tap, checked the flow out of them.

[Butch (cb)]

I don't really hold with stale fuel theories, but I guess someone out there will shout me down shortly. I've not fired mine up yet since around last October time so could yet get bitten myself. Always galling though, nothing has been changed but now it don't work. A quick look at magneto and points for general cleanliness perhaps?

I'm Braintree btw so guess you are not a million miles away.

[muskrat]

G'day Mick. I'm with Ethelred's views. It started so easy after the carb clean because of all that highly flammable carby clean in there. If your fuel has ethanol in it and is older than a month I'd replace it.
Cheers

[mick43]

many thanks all - I'll be following your words of advise...

[unclerob]

Hi Mick, I work with marine engines and nowadays see carb problems far more often than I used to....which I put down to the ethanol content in fuel. Especially corroded and blocked jets that won't clean just with carb cleaner...the first thing I'd check is the pilot jet....that's the one under a small nut just in front of the main jet....good luck!

[mick43]

thank you..

a little update... drained tank and carb and filled with fresh fuel (95 RON).

took out and checked pilot and main jets - all super clean but blowed then through anyway...

checked for spark and timing - all ok..

but... still won't start...  plugs getting damp... loads of compression.... tried squirt of carb cleaner down carb, tried 'super-choking' (rag over air intake)...

lots of kicking, lots of fuel smell.... so will now leave plugs out to let her dry out completely... and try kicking over again on Tues (busy tomorrow)...

I've also been advised to drain again and replace with 'super unleaded' - which I will do..

so mystery remains... she was running so sweet.. tick over and pulling away...

I'll update later next week on progress....

[muskrat]

Silly question but.
 Have you blown out all the holes that the jets come out of? Fuel taps and hose clear, cap still vents? Wasp nest in air filter (DAMHIK)?
Cheers

[BSA_54A10]

thank you..



 plugs getting damp... loads of compression.... SNIP... so will now leave plugs out to let her dry out completely... and try kicking over again on Tues (busy tomorrow)...

I've also been advised to drain again and replace with 'super unleaded' - which I will do..

so mystery remains... she was running so sweet.. tick over and pulling away...

I'll update later next week on progress....

Waste of time.
Once the plugs are wet with fuel it is all over red rover unless you burn them off.
Modern "fuel" which is not petrol is very conductive at cylinder compressions.
modern fuels ( which are nothing like petrol ) will evaporate down to a foul smelling gum that will block off every hole it is left in which is why it is essential that you run the carby dry if you are not going to use it for a while. Even worse if it does not evaporate it is electrically conductine so have the same effect as leaving the carb full of seawater, galvanic corrosion + bacterial corrosion to boot.

[bsa-bill]

Once the plugs are wet with fuel it is all over red rover unless you burn them off.

Quite a few hear have had this problem  me included, best reason I've heard so far would be the ceramic insulator bit in the cylinder not glazed nowadays so gets wet and soaks in.
Got me wondering if a spray on glaze is available, would probably cure in the engine -- maybe

any way i went electronic (Pazon) and can use Iridium plugs, do believe they are glazed, whatever - the thing starts fine now even has to be quite rich with a really good flood, probably I need to look at tuning a bit more

[Ethelred]

If the carb is perfectly clean and everything was running perfectly before you put it away, so the timing's OK, and there's good compression on both sides, so no sticky valves, then that only leaves electrics. It is possible for the condenser in the magneto to begin to fail just due to old age, which can give the symptoms you describe. Several magneto rebuilders on this site who can advise further. You can have a situation where you can see a spark on the outside but it doesn't spark under compression. As previously advised, check the points are clean and good luck on your Tuesday workout 

[beezermacc]

Carburettor problems nearly always turn out to be electrical..........!

[mick43]

thanks all again....

so I filled with super leaded, and heated plugs up on the gas hob... she fired up second kick... but...

...only run smooth with a little choke... on tick over without choke she was lumpy with a little black smoke... unscrewed air screw a bit and no impact... got lumpier and relied more on choke to run.. and after a few minutes conked out...  I gave a little tickle to see if float chamber was full, and it was (fuel there straight away..) so maybe it is condenser breaking down...?

I tried one or two kicks only to see if she would start and didn't....

[mick43]

I've been given name of family run bike mechanic/workshop who have been up and running for bikes (especially BSA) for 60yrs...

I gave them a ring and he confirmed 'black smoke' is normally fuel... and one know issue is if pilot jet is screwed in too tight (soft end can damage.....)

In any event, th bike was running perfect and I want it to do the same again, so she goes to their workshop next Tuesday...

I'll report back here what the problem(s) were to help any others...

Thanks again for kind words of advice...  watch this space 

[BSA_54A10]

FWIW if the pilot jet is clean & the carb adjusted properly a very small mov ement of the piot needle will make a drastic change to the engine.
If it makes little difference then the pilot circuit is blocked some where.